A review of the territory's Working with Vulnerable People system, five years after it began, was tabled in the Legislative Assembly last week.

The review, by consultants at Nous Group, found that while the government in 2012 expected the number of cards issued would be about 42,000, there have actually been 140,000 such registrations and 95,000 currently on the books.

The background checks, which centre on a National Police History Check, are valid for up to three years and are used by people who work with children, the elderly and people with a disability in both paid employment and as a volunteer.

In the 2016-17 year, the government processed 38,577 registrations and checked 5312 cards, finding 413 instances of 'non-compliance', mostly related to people failing to produce their card on request or not holding a valid one.

The government also issued one infringement notice last financial year to a person for failing to notify the Commissioner for Fair Trading within 10 days of being charged with a relevant offence.

While the review found the scheme was well supported, the unexpectedly high number of registrations has meant Access Canberra, which administers it, "cannot deliver the scheme within its budget".

At the time of the review, there were just four government staff running the scheme, and the review report urged the government allocate an extra $1.5 million to meet the demand - money the government allocated in the 2017-18 budget.

It also said the high numbers of registrations suggested ACT employers were making blanket decisions for all staff to be registered "regardless of whether they are required to".

Given the huge demand and lack of resources, the consultants recommended the registration period be extended to five years as a key reform that would not alter the existing protections or increase the risks to vulnerable people "to an unacceptable level".

Such a move, Access Canberra staff told Nous, would create a 40 per cent saving in operating costs, while a 10 year period could create up to 70 per cent savings, but that was "not appropriate or feasible".

Since it started in 2012, the scheme has also stopped 29 people with "relevant criminal histories" from being registered during risk assessments, while Access Canberra's compliance program has ended 23 registrations.

While people can be refused a card if they have a relevant criminal history, such as sexual assault of a child, the review also recommended widening the criteria for disqualifications or rejection for more "serious criminal history offences".

That move would make it easier to run the scheme, but the report did not identify which specific offences should be included in the proposed criteria.

That criteria should instead be decided through national reforms to harmonise all jurisdiction's schemes, work expected to take about two years to complete, in response to the Royal Commission into Institutional Responses to Child Sexual Abuse.

It also recommended improving information sharing, both between the ACT and other jurisdictions and between the territory government, police and the courts that deal with it on a daily basis.

A spokesman for children's minister Rachel Stephen-Smith said the government was working on reforms expected to be introduced in the Legislative Assembly next year.

"A comprehensive implementation and community engagement plan is being developed to ensure the impact of the proposed legislative changes is well understood, including the impacts on employees, employers, volunteers and community organisations," he said.